The present invention relates to a forming die unit adjusting method and a forming apparatus, and in particular, to an adjusting method for a forming die unit which can adjust accurately a forming die unit for forming, for example, an optical element, and to a forming apparatus.
In an forming apparatus that generates a forming such as, for example, a highly accurate optical element through forming, it is extremely important to construct a forming cavity, concerning plural forming dies which mold materials, by combining them accurately without eccentricity. As a method to lower the extent of eccentricity of this forming die, an improvement of accuracy of machining for parts of a die which constitute the forming cavity has been made conventionally, and this method has been attempted to realize highly precise forming for the forming.
However, when improving machining accuracy, it is normally a limit to put a machining error for parts of a forming die within a few microns, and it was a limit to attain parts machining accuracy of about 1 micron even when consuming labor of manual fitting and offering specific technical skill. The reason for this is as follows; when a forming cavity is constructed by incorporating parts of a forming die, a shift (deviation of the direction perpendicular to an optical axis) and a tilt (inclination of an axial line) both corresponding to dispersion of machining accuracy are generated in accuracy of eccentricity of mutual forming dies. In particular, in the case of shift eccentricity, it is possible to improve accuracy up to about 1 micron by consuming time and labor as stated above, but in the case of tilt eccentricity, it was extremely difficult to secure incorporating accuracy of 1 minute angle or less.
In contrast to this, in the following patent document 1, there is disclosed a structure wherein a mount of the upper die is made to be spherical, and a receiving surface of a base is made to be a spherical surface so that the mount may be enchased therein and fixed by bolts through a clamp member. In this technology, the mount can be rotated on the receiving surface, and a tilt of the upper die for the lower die can be adjusted accordingly.
(Document 1)
Tokkaihei No. 8-259245
However, in the conventional technology stated above, when the clamp member that holds the mount is tightened by bolts after adjusting the tilt, the mount is moved by uneven forces of the plural bolts, causing a fear that the tilt angle adjusted with great efforts may be changed.